// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2014 Benoit Steiner <benoit.steiner.goog@gmail.com>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#ifndef EIGEN_CXX11_THREADPOOL_THREAD_POOL_INTERFACE_H
#define EIGEN_CXX11_THREADPOOL_THREAD_POOL_INTERFACE_H

namespace Eigen {

// This defines an interface that ThreadPoolDevice can take to use
// custom thread pools underneath.
class ThreadPoolInterface
{
  public:
	// Submits a closure to be run by a thread in the pool.
	virtual void Schedule(std::function<void()> fn) = 0;

	// Submits a closure to be run by threads in the range [start, end) in the
	// pool.
	virtual void ScheduleWithHint(std::function<void()> fn, int /*start*/, int /*end*/)
	{
		// Just defer to Schedule in case sub-classes aren't interested in
		// overriding this functionality.
		Schedule(fn);
	}

	// If implemented, stop processing the closures that have been enqueued.
	// Currently running closures may still be processed.
	// If not implemented, does nothing.
	virtual void Cancel() {}

	// Returns the number of threads in the pool.
	virtual int NumThreads() const = 0;

	// Returns a logical thread index between 0 and NumThreads() - 1 if called
	// from one of the threads in the pool. Returns -1 otherwise.
	virtual int CurrentThreadId() const = 0;

	virtual ~ThreadPoolInterface() {}
};

} // namespace Eigen

#endif // EIGEN_CXX11_THREADPOOL_THREAD_POOL_INTERFACE_H
